In this chapter, the vertebrate model organism, zebrafish (Danio rerio), will be discussed in the context of its amenability to developmental biology and toxicology. Numerous advantages make zebrafish favorable for research in these areas, including optical clarity and rapid development. Zebrafish are ideal for the study of the major stages of development as well as neurodevelopment, having comparable stages and components of the central nervous system to higher vertebrates. An important feature of the organism for neurodevelopmental research is that it has complex, well-defined behaviors. Research using zebrafish for developmental toxicology has expanded in part because of the many benefits that make the model favorable for developmental biology discoveries. Chemical screens in embryos can be performed using automated techniques, providing developmental toxicity data for the large number of chemicals lacking this information. As advancements continue to increase the throughput of analyses, zebrafish are positioned to further expand the knowledge of vertebrate developmental biology and toxicology.